Fig. 6.

Correlation analyses for $t$-values between oxy-Hb and deoxy-Hb signals among 44 channels. (a) Correlation analysis for the NMT using the peak delay (Oxy · Deoxy: ${\tau }_p=6$) for the typical condition. (b) Correlation analysis for the VFT using the peak delay (Oxy · Deoxy: ${\tau }_p=6$) for the typical condition. (c) Correlation analysis for the NMT using the optimal peak delay (Oxy: ${\tau }_p=6$, Deoxy: ${\tau }_p=17$). (d) Correlation analysis for the VFT using the optimal peak delay (Oxy: ${\tau }_p=10$, Deoxy: ${\tau }_p=24$).